1. Field of the Invention
The present invention relates to a semiconductor laser which can be used, for example, to excite an optical amplifier using an Er-doped quartz optical fiber.
2. Related Background Art
Optical amplifiers using Er-doped quartz optical fibers have attracted a great deal of attention as a core technology for an optical communication system of a future generation. As a pump source for the optical amplifier, a semiconductor laser having an operating wavelength of 1.48 or 0.98 .mu.m is used. A 0.98-.mu.m semiconductor laser currently reported has an active layer consisting of GaInAs and a cladding layer consisting of AlGaAs or GaInP.
Semiconductor lasers using AlGaAs as a cladding material have good initial characteristics and high reliability on the average. However, some are suddenly deteriorated when being energized. At present, they cannot be removed by initial screening. To the contrary, such an accidental deterioration is expected to occur less frequently in semiconductor lasers using GaInP or AlGaInP as a cladding material.
However, in the semiconductor lasers using GaInP or AlGaInP as a cladding material, the operating voltage is high and the morphology tends to be degraded.